1. Field of the Invention
This invention relates generally to virtual storage, and more particularly to managing virtual volumes in a storage area network.
2. Description of the Related Art
One of the causes of poor asset use in an information technology setting is the fact that host operating systems expect to exclusively “own” devices attached to them. These operating systems jealously guard their storage, holding it captive to prevent other servers that have exhausted their capacity from tapping into available space on adjacent servers. As a result, organizations waste substantial portions of their investments buying more and more storage, creating a difficult environment to manage. Storage is also wasted because it is difficult or time-consuming to move storage devices between servers.
Some conventional systems provide “virtual local storage.” These systems typically implement hard mappings or other mechanisms that appropriately route requests to access the remote storage device. The systems also implement access controls, which ensure that specified disks or partitions belong to assigned host devices. The “virtual” element in these systems is that physical disks are made to appear as though they are locally available to a host device. Although these systems purport to provide speed based advantages over traditional client server models that allow remote access to disks, they still have the problems identified above, as they merely provide another way to allocate physical storage to host devices on a piecemeal basis, whether the physical storage is whole disks or partitions of disks. For example, if an administrator has 100 units of physical disk space available, he might allocate 30 units to a first user, 30 units to a second user, and 40 units to a third user by creating a mapping that routes their respective client devices to the physical disk space. Thus, even with these systems, the allocations will be “jealously guarded” by the assigned client devices, and the allocation is limited by the sum of the individual storage allocations. Additionally, if a new allocation or reallocation is sought, the hard mappings must be updated and various procedures would be required to retain the integrity of the data stored by each user.
What is needed is a way to decrease the cost of storage devices, to maximize the usage of existent storage devices in a computer network, and to easily and effectively add storage devices without having to shut down the existing storage system.